Preformed-particle-gel (PPG) treatments have been successfully used in injection wells to reduce excessive water production from high-temperature, high-salinity fractured reservoirs. However, PPG itself cannot be used in fractured producers because it tends to wash out after the wells resume production. Therefore, we proposed to combine curable resin-coated particles (CRPs) with PPG to control water production from fractured producers. In this paper, millimeter-sized tubes and fractured carbonate cores were designed to comprehensively investigate water-plugging behaviors of the combined system under the conditions of various fracture parameters and PPG/CRP sizes. Particular attention was given to control the PPG washout after production was resumed. The results showed the cured CRPs could generate immobile packs in fractures and dramatically mitigate the PPG washout. The small size of the CRPs and the small ratio of CRP size to tube diameter contributed low permeability and homogeneity to CRP packs. Meanwhile, the less-permeable and more-homogeneous CRP pack, as well as the larger-sized PPGs, contributed to a higher PPG breakthrough pressure gradient. Moreover, some of the PPG particles blocked in the CRP packs could be released through high-speed brine injection from producers, which indicated the recoverability of the water plugging. This study provides a promising approach to reduce the high-water-cut problem in fractured producers.

Preformed particle gel (PPG) treatment has been well-recognized as an efficient method to reduce excessive water production in fractured reservoirs. However, previous research on its plugging efficiency was mainly conducted in open fractures. In this paper, calcite-filled fracture models were designed to comprehensively investigate the water plugging performance of PPG in partially filled fractures which are extremely common in fractured reservoirs. Systematic plugging performance tests have proceeded under various calcite-filling conditions. The results show that the calcite particles can improve the breakthrough and retention of the PPG as well as the plugging efficiency. With increased size and concentration of the calcite particles, the PPG breakthrough pressure gradient increases, and the fracture permeability decreases. When the ratio of average calcite particle diameter to fracture width (R-C) is small (0.15), the fracture permeability is difficult to be further reduced by increasing PPG concentration or PPG size. However, when the R-C increases to 0.21, the plugging performance in fractures filled with more calcite particles or PPG particles, especially the latter, is better than that filled with larger calcite particles. This study provides new insight into the PPG treatment and will contribute to the water control in fractured reservoirs.

通过实验和数值模拟方法,研究了低密度调流剂颗粒在碳酸盐岩缝洞型油藏裂缝中的运移沉降规律.在平板裂缝模型中开展不同携带液黏度和密度的调流剂颗粒输送实验,利用高清摄像机观测颗粒在裂缝进口和远端流场中的流动特征,以及砂堤的堆积位置和高度.为了能够量化颗粒输送过程中的运动参数,建立了基于CFD-DPM的颗粒输送模型,并进行流体和颗粒相的双向耦合模拟,量化了在注入速度、携带液密度和黏度、颗粒直径等因素作用下调流剂颗粒的速度和沉降距离,进而得到了各因素与颗粒流的沉降剖面和颗粒沉降百分比之间的关系.